Molecules, Blood and Gas Exchange

Unit F211

The Blood(1.1.1)

Studying cells can provide valuable information about health.

Learning Objective

(1.1.1)a. describe how blood samples are taken and

blood smears (films) are made.

Blood_Test.3gp

Task

In your group, come up with a strategy to describe how blood samples are taken.

REMEMBER TO USE ALL KEY WORDS.

Learning Objective

(1.1.1)a. describe how blood samples are taken and blood smears

(films) are made.

d. describe the structure, as seen with a light microscope, of red blood cells (erythrocytes), neutrophils, lymphocytes, monocytes and macrophages as specialised cells with particular functions related to their structures.

Task

• In group of two, Read how to make a blood smear/ blood film.

• Practice making a blood film using the equipments provided.

Task

Now, write step by step method to make a blood film. You are to work individually.

Task

Compare your procedure with your partner. Use the book to mark your partner’s work.

Differential Stain

Erythrocytes• Biconcave discs.• Relatively large surface area

to volume ratio.• Cytoplasm is packed with a

pigment, a protein called haemoglobin.

• Mature erythrocytes have no nucleus. Very small and flexible.

Leucocytes

Neutrophils• Have small granules in the

cytoplasm.• Engulf microorganisms by

phagocytosis.

Lymphocytes• Have a large, darkly stained

nucleus surrounded by a thin layer of cytoplasm.

• There are two kinds of lymphocytes, T and B lymphocytes. Both look the same.

• B lymphocytes produce antibodies.

• T lymphocytes have several functions including cell destruction.

Monocytes• Are the largest kind of

leucocyte.• They have large, been-

shaped nucleus and clear cytoplasm.

• They spend 2-3 days in the circulatory system, then they move to the tissues.

• In the tissues, they become macrophages, engulfing micro organisms and other foreign materials

Identify the cells

Task

In groups of two, use the bio viewer, look at the blood films, identify the different blood cells and draw and label them.

Under each diagram, list at least two features with explanation.

Homework

• Read information from work sheets and answer questions 1.3-1.6.

• Due next Wednesday.

Calculating Magnification

• 1.1.1.g:

calculate the linear dimensions and magnification of drawings or photographs of

cells

How to calculate magnification?

Magnification=

Rearrange the formula to find the real size of the structure.

Size of the structure in the pictureReal size of the structure

Remember

A micrometer (µm) is one millionth of a meter. 1 1µm= 10-⁶ m

1 µm= 10 -³ mmAlways measure the structure in millimetres .

This means you can convert this to micrometers by multiplying by 1000, i.e. adding 3 zeros.

Task

Answer questions 1 and 2 from the spread.

Homework

Produce a booklet to explain to a patient about her/ his blood test. You should include how to take a blood sample, make a blood film and stain it, also, explain how to identify blood cells from the blood smear. You should include diagrams.

Due next Thursday.

Using a Haemocytometer

1.1.1 c

Learning Objectives

describe the use of a haemocytometer to count the numbers of erythrocytes and leucocytes (to include details of dilution);

Haemocytometer

Calculating the number of erythrocytes in 1mm³ of the original blood sample

The triple lined squares measure exactly 0.2 x 0.02 mmThe platform is exactly 0.1 mm below the cover slip. This means when you view one of the triple lined squares under the microscope, you are looking at a volume of exactly0.1x0.2x0.2 mm = 0.004mm³

Number of RBCs in the original sample in 1 mm³= 1/0.02 x number of cells counted in five triple lined squares x dilution .

Remember the dilution is 200

Calculating the number of leucocytes in 1mm³ of the original blood sample

Count the number of WBCs in the four corner squares. These squares measure exactly 1x1 mm. the depth of the chamber is 0.1mm. This means that each square has a volume of 1x1x0.1 = 0.1mm³

Number of WBCs in the original sample in 1 mm³= 1/0.4 x number of cells counted in four corner squares x dilution .

Remember the dilution is 20

Homework

Homework task: Pupils to write a detailedmethod in order to enable another studentto repeat the process and generate accurate

and reliable data

Lipids

1.1.2 t

(t) describe, with the aid of diagrams, the basic structure of glycerol and fatty acids;

(u) outline the formation of triglycerides by the condensation reactions between glycerol and fatty acids;

List the types of molecules you need to break down (digest) from your food.

Introduction to lipidsLipids are a diverse group of compounds that are insoluble in water but soluble in organic solvents such as ethanol.

The most common types of lipid are triglycerides (sometimes known as true fats or neutral fats), but other important lipids include waxes, steroids and cholesterol.

Like carbohydrates, lipids contain carbon, hydrogen and oxygen, but they have a higher proportion of hydrogen and a lower proportion of oxygen.

The structure of triglycerides

The structure of phospholipids